The invention herein relates to relatively thick, non-woven fiber padding sheets which are typically used as underlay padding in upholstered furniture or within the upholstered seats of automotive vehicles, or as soundproofing material within the bodies of automotive vehicles. In the past, this type of padding material has been made of loose fibers obtained by shredding cotton and synthetic fiber cloths and thereafter matting or felting the fibers together. The fibers were bonded together, that is, at their points of intersection, by means of resinous binding materials.
The resinous binding materials which were used to bond together the fibers of the non-woven padding sheets, were typically phenolic based or latex based materials, usually applied in a dry powder form, although in some cases, sprayed wet and then dried.
The conventionally used process for forming such fibers involves first breaking open bales of scrap cloth and then shredding the cloth within shredding machinery. The fibers are then mixed together in a blending machine to obtain as uniform a blend as possible. Thereafter, the resinous material is blended in, typically in the range of roughly 20% by weight as compared to the cloth fibers.
The fibers and resinous bonding material are deposited in a loose sheet form in a non-woven fiberous material matting machine which includes a conveyor for moving the sheet through a heater and equipment for compacting the sheet to sepcified thickness. In the past, either heated rollers or heated guide plates were used to activate the bonding resin and to reduce the thickness of the sheet to either the desired dimension or close to the desired dimension. The setting of the resin within the heater or thereafter by air blast cooling, along with any necessary compacting to final thickness, resulted in the padding sheet being completed.
The completed padding sheet is ordinarily rolled into a thick roll for later use in sheet form or alternatively is immediately die cut to required sizes and shapes, as for example, to fit within the door or under the hood of an automobile for soundproofing, or within a particular size and shape upholstered piece.
By way of an example, a typical non-woven padding sheet may run roughly 27 to 180 grams per square foot and may vary in thickness from one quarter inch through one inch, approximately. The weights and the thicknesses vary depending upon the uses to which the padding is put, that is, as a soundproofing material, an underlay material or the like.
Typical non-woven padding materials of the type involved in the invention herein, are made of blends of roughly 80% by weight of cotton or synthetic fiberous materials, and 20% by weight of the resin which acts as the binder. As mentioned, the fibers normally come from scrap materials, such as rags or scrap cloth.
In the conventional system for forming such padding, the resultant padding material is relatively easily torn or transversely separated or delaminated, it has relatively low strength and therefore must be handled carefully because of its fragility. Moreover, the presently used conventional resins are petroleum based materials which have been increasing in price in recent times. Moreover, such materials are relatively difficult to handle when in dry powder form. Particularly, in the case of conventional phenolic powder and the like materials, there is a dust problem resulting from the dry powder being lifted into the surrounding atmosphere and therefore, the handling of floating dust around the matting equipment is troublesome.
Thus, the invention herein is concerned with an improved padding and method of making same, which follows the prior art or conventional procedure and utilizes conventional manufacturing equipment, except for an improved bonding system which is described below in this specification.